Anti-flashover ring installation tool and method for using the same

ABSTRACT

A tool ( 10 ) for installing an anti-flashover ring ( 140 ) onto a cylindrical device includes a housing ( 12 ) with an inner wall ( 24 ) with an extending edge ( 26 ). A plunger assembly ( 50 ) is slidably coupled to the housing ( 12 ) and carries the ring ( 140 ). The cylindrical device or bushing insert is received in the housing and the plunger assembly positions the ring onto the cylindrical device and the extending edge presses the ring onto the cylindrical device. A rod axially disposed in the housing and fixed to the plunger assembly is received in a bore ( 119 ) of the bushing insert ( 110 ) and assists in the positioning of the ring. The plunger assembly ( 50 ) includes a plunger ( 52 ) having a closed end ( 54 ) opposite an open end, the plunger has an interior plunger wall ( 60 ) with a spring lip ( 66 ). A holding collar ( 90 ) is slidably received in the plunger and a collar spring ( 100 ) is disposed between the plunger and the holding collar for biasing the holding collar. The holding collar carries the ring until engaged by the bushing insert.

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 09/235,092to Edward H. Decker filed on Jan. 21, 1999, now U.S. Pat. No. 6,256,852the subject matter of which is herein incorporated by reference, andclaims the benefit thereof under 35 U.S.C. §120.

TECHNCAL FIELD

This invention relates generally to a tool for mounting a safety deviceon high voltage electrical equipment. Specifically, the presentinvention relates to a tool for installing an anti-flashover ring thatfits on an electrical accessory product. More particularly, the presentinvention relates to an installation tool that allows installation ofthe anti-flashover ring at a safe distance from the high voltageelectrical equipment whether energized or de-energized.

BACKGROUND ART

As discussed in co-pending U.S. application Ser. No. 09/085,801,entitled “Anti-Flashover Ring For A Bushing Insert” and assigned to theAssignee of the present application, which is incorporated herein byreference, there is a need to eliminate electrical arcing duringdisconnection of a live source of power. As discussed therein, ananti-flashover ring for an accessory product such as a bushing insertwas developed to significantly reduce this risk.

Electrical accessory products such as bushing inserts, which aretypically rated for 15 kV, 25 kV, or 35 kV, are all dimensionally sizedaccording to ANSI/IEEE Standard 386. This standard defines the variousdimensional and electrical operating aspects of the electrical accessoryproducts so that products from different manufacturers may beinterchangeable. Even with these standards, it will be appreciated thatthere are slight dimensional variations between accessory products fromdifferent manufacturers.

There are several ways in which the anti-flashover ring can be installedon a bushing insert. The easiest way to install the ring is to place iton the bushing insert before the bushing insert is installed on highvoltage electrical equipment such as a transformer. However, it will beappreciated that there are many such bushing inserts and other relatedaccessory products already installed in the field. In order to installthe anti-flashover ring onto these installed bushing inserts and thelike, safe operating practice requires that all downstream equipment bede-energized. Next, the bushing insert may be removed from thetransformer and the anti-flashover ring is installed on the bushinginsert by hand. The bushing insert is then reinstalled and thedownstream equipment is re-energized. As will be appreciated by thoseskilled in the art, this is a very expensive and time-consuming processand one not favored by public utility companies. Alternatively, theanti-flashover ring could be installed without removing the bushinginsert from the high voltage equipment, but this is considered adangerous option and safety practices of public utilities generallyprevent this option. In order to implement this option, an operatorwould be required to hand install the anti-flashover ring directly ontothe connected bushing insert. Hand installation is also undesirablebecause the dimensional variations of the bushing inserts may requirespecial care by the installer to ensure that the ring is uniformly andproperly mounted to the bushing insert.

It is thus desired in the art to provide a tool which may be adaptablefor operation or use by a “hot stick” or insulated operation tool.Furthermore, it is desired that the tool and its method for use ensurethat the anti-flashover ring is properly installed onto the accessoryproduct in an efficient and secure manner.

SUMMARY OF INVENTION

In light of the foregoing, it is a first aspect of the present inventionto provide an anti-flashover ring installation tool and method for usingthe same.

Another aspect of the present invention is to provide an anti-flashoverring installation tool that maybe used with an insulated hot stick toallow safe and proper installation of the ring.

Yet another aspect of the present invention is to provide aninstallation tool, as set forth above, which provides alignment featuresprior to installing the ring onto an accessory product such as a bushinginsert.

Still another aspect of the present invention is to provide aninstallation tool, as set forth above, that includes a housing with aspring-biased plunger assembly that positions the ring onto the bushinginsert and then presses the ring onto the bushing insert.

Still yet another aspect of the present invention, as set forth above,is to provide the plunger assembly with an insert cavity having acoaxially extending rod that is received by the bushing insert duringinstallation.

A further aspect of the present invention is to provide an installationtool, as set forth above, in which the plunger assembly includes aspring-biased holding collar which frictionally carries the ring andwherein the holding collar is slidably moveable within the plungerassembly.

Still a further aspect of the present invention is to provide aninstallation tool, as set forth above, wherein the holding collarcontacts a surface of the bushing insert and is pushed back while aplunger in the plunger assembly positions the ring onto a shoulder ofthe bushing insert.

An additional aspect of the present invention is to provide aninstallation tool, as set forth above, in which the housing provides afinal push of the anti-flashover ring until seated and frictionally heldby the bushing insert.

The foregoing and other aspects of the present invention, which shallbecome apparent as the detailed description proceeds, are achieved by atool for installing a ring onto a cylindrical device, comprising ahousing having an inner wall with an extending edge, the inner walldefining an opening, a plunger assembly slidably coupled to the housing,the plunger assembly carrying the ring wherein the cylindrical device isreceived in the opening and the plunger assembly positions the ringabout the cylindrical device and the extending edge presses the ringonto the cylindrical device.

Other aspects of the present invention are attained by an installationtool for installing an anti-flashover ring on an electrical accessoryproduct such as a bushing insert, the tool comprising a housing having acap at one end and a cup at an opposite end, the cap having a holetherethrough to receive a remote operating tool, the cup having a closedend with a bore therethrough adjacent the cap, and an open end oppositethe closed end, the cup having a substantially flat cup edge at the openend, a rod slidably moveable in the bore, one end of the rod slidablymounted in the cap, a plunger slidably received in the cup, the plungerhaving a closed end with a rod hole therethrough, the rod fixed to therod hole, the plunger having an open end opposite the plunger closedend, the plunger open end facing the same direction as the open end ofthe cup, the plunger open end having an insert cavity into which the rodcoaxially extends, the plunger having an interior plunger wall with asleeve lip and a spring lip, a spring disposed between the plunger andthe cup, a sleeve mounted to the sleeve lip, a holding collar slidablymovable between the sleeve and the interior plunger wall and retainedwithin the plunger, and a collar spring disposed between the holdingcollar and the spring lip, the holding collar frictionally receiving thering, wherein an operator positions the installation tool such that therod is received by the bushing insert, the holding collar aligns thering onto a shoulder of the bushing insert, wherein the shoulder pushesthe holding collar until the plunger engages the anti-flashover ring tocomplete positioning of the ring onto the shoulder, and wherein theshoulder and the ring slidably move the plunger until engaged by the cupedge which completely pushes the ring onto the shoulder.

Still another object of the present invention is attained by a methodfor installing an anti-flashover ring onto a bushing insert, wherein thering has an outer surface and an inner surface, and a shoulder wallextending inwardly from the inner surface, the shoulder wall having ashoulder surface, and wherein the bushing insert has a frusto-conicalportion with a bore therethrough, the frusto-conical portion terminatingat a shoulder which extends into a shielded collar, the methodcomprising the steps of positioning the ring on a spring-biased plungerassembly slidably received in a cup, the plunger assembly having aninsert cavity for receiving the frusto-conical portion and a rodextending substantially coaxially into the insert cavity, aligning thespring-biased plunger assembly onto the bushing insert by inserting therod into the bore, moving the plunger assembly until the ring ispositioned onto the shoulder, further moving the plunger assembly untilretracted within the cup wherein the cup pushes the ring onto theshoulder, and withdrawing the cup and the plunger assembly from theinsert.

These and other aspects of the present invention, as well as theadvantages thereof over existing prior art forms, which will becomeapparent from the description to follow, are accomplished by theimprovements hereinafter described and claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

For a complete understanding of the objects, techniques and structure ofthe invention, reference should be made to the following detaileddescription and accompanying drawings, wherein:

FIG. 1 is a cross-sectional elevation view of an anti-flashover ringinstallation tool;

FIG. 2 is an enlarged view of a plunger assembly end of the installationtool;

FIG. 3 is an assembly drawing of the installation tool;

FIG. 4 is a side view, partially in section, of a bushing insert mountedto high-voltage equipment;

FIG. 5 is a rear elevational view of an anti-flashover ring;

FIG. 6 is a side elevational view of the anti-flashover ring; and

FIGS. 7A-E show the installation tool in various positions duringinstallation of the anti-flashover ring on the bushing insert.

PREFERRED EMBODIMENT FOR CARRYING OUT THE INVENTION

Referring now to the drawings, and more particularly, to FIGS. 1-3, itcan be seen that an anti-flashover ring installation tool, according tothe present invention, is designated generally by the numeral 10. Thetool 10 is generally cylindrical in shape and may be fabricated from anon-conductive polymeric material. Although the tool 10 is adapted forinstalling an anti-flashover ring, it will be appreciated that the tool10 is structurally capable of installing any type of ring onto acylindrical device.

The tool 10 includes a housing 12 which is generally cylindrical inshape. The housing 12 includes a cap 14 which is closed at one end andopen at its opposite end. The cap 14 provides an axial bore 15.Extending from the closed end of the cap 14 is a tab 16 which has atransverse hole 18 therethrough. The hole 18 is employed to receive ahot stick or other operator tool to allow safe handling of theinstallation tool 10 away from the high-voltage equipment. Thisprecaution is taken even though the high voltage equipment is shut downat a remote distance from the equipment.

The housing 12 further includes a cup 20 which is secured to the cap 14by fastening devices 21. Of course, other means for securing the cup 20to the cap 14 could be employed such as adhesive, detents, clamps, orthe like. The cup 20 includes an outer wall 22 and an inner wall 24which are connected by a cup edge 26. In the preferred embodiment, thecup edge 26 is substantially flat and perpendicular with respect to theouter wall 22 and the inner wall 24. The cup 20 includes a cup base 28opposite the cup edge 26 so as to form a cup cavity or opening 30 withinthe cup 20. The cup base 28 has a hole 34 extending therethrough whichis aligned with the axial bore 15 of the cap 14.

A rod 36, which in the preferred embodiment is made of fiberglass orother non-conductive material, is slidably moveable in the cup base 28through the hole 34. It will be appreciated that the rod 36 ispositioned to be substantially co-axial with the inner wall 24. The rod36 includes an internally threaded bore 38 at one end which is oppositea tapered end 40. In assembling the installation tool 10, the rod 36 isinserted through the hole 34 and then a screw 40 fastens a flat washer41 and an O-ring 42 to the rod 36 to slidably retain the end of the rodin the cap. It will be appreciated that a pin, C-clip, or other devicewhich is larger in diameter than the hole 34 may be used to slidablyretain one end of the rod 36 in the cap 14. After this manufacturingstep is complete, the cup 20 is assembled to the cap 14 such that oneend of the rod 36 is captured within the cup 20. A rod spring 46 isdisposed over the rod 36 and positioned or biased at one end by the cupbase 28.

A plunger assembly, which is designated generally by the numeral 50, isbiasingly received within the housing 12. Generally, the plungerassembly 50 receives the anti-flashover ring and positions the ring uponthe bushing insert in a secure and efficient manner.

The plunger assembly 50 includes a plunger 52 which is substantiallytubular in shape. The plunger 52 provides a closed end 54 with a rodhole 56 extending therethrough. The rod 36 is received through the rodhole 56 and is held in place by a set screw 57 or other fasteningdevice. Alternatively, the hole carrying the set screw could extend allthe way through the base 54 and receive a press fit pin, wherein the rod36 is also modified to receive the pin. As such, the secured rod 36could be replaced by removing the pin. Of course, other fasteningdevices could be employed to hold the rod 36 in the plunger 52. Theplunger 52 includes an exterior plunger wall 58 which slidably movesadjacent the cup inner wall 24. An interior plunger wall 60 is connectedto the exterior plunger wall 58 by a tapered end 62. In other words, thetapered end 62 provides an angular transition from the exterior plungerwall 58 to the interior plunger wall 60. An inwardly-stepped spring lip66 and an inwardly-stepped sleeve lip 68 are provided by the interiorplunger wall 60. That portion of the interior plunger wall 60 betweenthe spring lip 66 and the sleeve lip 68 provides an internally threadedsection 69. The interior plunger wall 60 forms an insert cavity 70 whichallows positioning of the installation tool 10 over an electricalaccessory product. It can be seen that the rod 36 extends into theinsert cavity 70 and is substantially coaxial therewith. Movement of theplunger 52 is biased by the rod spring 46. The plunger assembly 50 isheld within the cup 20 by virtue of the rod 36 being fixed to the closedend and retention of the rod in the cap 14.

A sleeve, which is designated generally by the numeral 80, is disposedwithin and attached to the plunger 52. The sleeve 80 includes an outersurface 81 with external threads 82 which mate with the internallythreaded section 69 of the interior plunger wall 60. The sleeve 80provides an opening 83 therethrough. The sleeve 80 has a lip end 84which abuts the sleeve lip 68. An inner surface 85 of the sleeve of thesleeve 80 is substantially flush with that portion of the interiorplunger wall 60 adjacent the closed end 54. A shoulder 86 extends fromthe outer surface 81 at an end opposite the lip end 84.

A holding collar, which is designated generally by the numeral 90, isslidably received between the plunger 52 and the sleeve 80 whenassembled. The holding collar 90 includes an outer surface 92 and aninner surface 94. The holding collar 90 is cylindrical in shape and hasan opening 95 therethrough. A ledge 96 extends inwardly from the innersurface 94 at one end. The holding collar 90 provides a leading edge 98opposite the ledge 96. A collar spring 100 is disposed between the ledge96 and the spring lip 66.

In assembling the holding collar 90, the sleeve 80, and the collarspring 100 to the plunger 52, the holding collar 90 is slipped over thesleeve 80 such that the shoulder 86 abuts the ledge 96. The collarspring 100 is disposed over the outer surface 82 of the sleeve 80. Thissub-assembly is then inserted into the plunger 52 such that the collarspring 100 is biased by the spring lip 66. The sleeve 80 is positionedto abut the sleeve lip 68 and secured to the plunger 52 by the threadedinterconnection of section 69 and the threads 82. Alternatively,adhesive or other mechanical fastening devices could be used. When theentire installation tool 10 is assembled, it will be appreciated thatthe holding collar 90 is biased with respect to the plunger 52 and thatthe plunger 52 is biased with respect to the housing 12.

To fully understand the operation of the installation tool 10, referenceis now made to FIGS. 4-6. As best seen in FIG. 4, a bushing insert isdesignated generally by the numeral 110. The bushing insert 110 includesa semi-conductive shielded collar 114 that is substantially cylindricalbut may be slightly tapered. A semi-conductive shielded sheath 116extends from one end of the collar 114. The sheath 116 and the collar114 provide protection and a ground shield for the bushing insert 110. Anon-conductive frusto-conical portion 118 extends outwardly from theother end of collar 114 and terminates at an annular locking groove 120.A shoulder wall 122 forms the connection between the collar 114 and thefrusto-conical portion 118. Shoulder wall 122 is disposed at asubstantially right angle with respect to collar 114 and joins thefrusto-conical portion 118 in a small chamfer. The bushing insert 110provides internal electrical connection components therethrough toprovide a medium for electrically connecting other connectors toelectrical distribution equipment, such as transformers and the like. Itwill be appreciated that there is a bore 119 extending within thefrusto-conical portion to a female-type contact within the insert 110.

In order to prevent arcing or flashing between the shielded collar 114and mating electrical contacts, an anti-flashover ring, designatedgenerally by the numeral 140, is employed. As best seen in FIGS. 5 and6, the ring 140 is generally circular in shape and may be fabricatedfrom a non-conductive material such as a thermoplastic elastomer.Whatever material is used, it is likely slightly expandable to fit overvarious sized bushing inserts or other electrical accessory products.Other suitable polymeric materials are also contemplated by the presentinvention. The ring 140 includes at least one passageway or notch, eachindicated generally by the numeral 142, that functions to prevent avacuum from being formed between the connector mounted onto the bushinginsert 110 when separated from each other with the ring 140 properlypositioned on the bushing insert 110.

The ring 140 includes a ring-shaped body 144 that has an outer surface146 and at least one inner surface 148. A notch 142 extends transverselyalong outer surface 146 to provide an open path through body 144. In thepreferred embodiment, each passageway or notch 142 extends in alongitudinal direction through body 144. The longitudinal directionbeing substantially perpendicular to all the radii of body 144. In otherwords, the passageways 142 are radially disposed along the outerperiphery of body 144. The passageways 142 may be in the form of thenotches as depicted in the drawings or may be channels interior to thebody 144. The passageways may further be disposed along the innersurface 148.

The body 144 includes a pair of opposed side walls 150 and 152. Thepassageways 142 are formed in body 144 and are open to the outer surface146 and extend from one side wall 150 to the other side wall 152, eachpassageway 142 includes substantially parallel side walls 156 that areconnected to a bottom wall 158 that is substantially perpendicular toeach side wall 156. The body 144 further includes a shoulder that isformed by a shoulder wall 160 that extends radially inwardly from theinner surface 148. The shoulder wall 160 provides a shoulder surface162.

Referring now to FIGS. 7A-E, the process for using the installation tool10 is presented. As a first step, the operator employs a hot stick orthe like to grasp the cap 14. Next, the user positions the ring 140 untoholding collar 90. It will be appreciated that the outer diameter of theholding collar 90 is equal to or slightly larger than the inner diameterof the shoulder surface 162. As such, once the user places the ring 140onto the holding collar 90, the tool can be moved about without the ringfalling off. Of course, the ring 140 can be easily withdrawn with properapplication of a pulling force.

In FIG. 7B, the operator then positions the tool 10 over the bushinginsert 110. As this is done, the rod 36 is inserted into the bore 119provided by the frusto-conical portion 118. This functions to align thetool 10 onto the bushing insert 110.

As seen in FIG. 7C, the operator continues to move the tool 10 until theholding collar 90 comes in contact with the shoulder 122. At this time,the outer surface 146 is aligned over the collar 114. As the tool 10 ispushed forward, the shoulder 122 pushes the holding collar 90 and thecollar spring 100 positioned between the outer sleeve surface 82 and theinterior plunger wall 60 is compressed. When the holding collar 90becomes flush with the tapered end 62, the tapered end edges into thering 140 and causes it to slightly bow out from its bottom. This helpsthe ring to fit around the shoulder 122 of the bushing 110.

As seen in FIG. 7D, the applied force of the plunger 52 initially pushesthe ring 140 onto the bushing. As the tapered end 62 engages the ring140 and the shoulder wall 122, the plunger 52 is pushed back into thecup 20. Once the tapered end 62 is flush with the cup edge 26, the cup20 presses and seats the ring 140 into its final position. At this time,the ring is seated and frictionally held in place by the collar 122 andthe tool is released from the bushing insert as seen in FIG. 7E.

As can be seen from the foregoing structure of the tool 10 and itsoperation of use, several advantages of the present invention arereadily apparent. Primarily, use of the tool allows for installation ofthe anti-flashover ring onto a bushing insert without completelyde-energizing a transformer associated with the bushing insert. Thissaves down time and accordingly, costs for the utility. Anotheradvantage of the present invention is that it is adaptable for use witha hot stick to allow an operator to install the anti-flashover ring at asafe distance. Still yet another advantage of the present invention isthat it ensures that the anti-flashover ring is properly installed in auniform and efficient manner.

Thus, it can be seen that the objects of the invention have beenattained by the structure and its method for use presented above. Whilein accordance with the Patent Statutes, only the best mode and preferredembodiment has been presented and described in detail, it is to beunderstood that the invention is not limited thereto or thereby.Accordingly, for an appreciation of true scope and breadth of theinvention, reference should be made to the following claims.

What is claimed is:
 1. A method for installing an anti-flashover ringonto a bushing insert, wherein the ring has an outer surface and aninner surface, and a shoulder wall extending inwardly from said innersurface, said shoulder wall having a shoulder surface, and wherein thebushing insert has a frusto-conical portion with a bore therethrough,the frusto-conical portion terminating at a shoulder which extends intoa shielded collar, the method comprising the steps of: positioning thering on a spring-biased plunger assembly slidably received in a cup,said plunger assembly having an insert cavity for receiving thefrusto-conical portion and a rod extending substantially coaxially intosaid insert cavity; aligning said spring-biased plunger assembly ontothe bushing insert by inserting said rod into the bore; moving saidplunger assembly until the ring is positioned onto the shoulder; furthermoving said plunger assembly until retracted within said cup whereinsaid cup pushes the ring onto the shoulder; and withdrawing said cup andsaid plunger assembly from the insert.
 2. The method according to claim1, farther comprising the step of: biasing a holding collar within saidplunger assembly, wherein said positioning step includes the step offrictionally fitting the ring onto said holding collar, wherein theshoulder initially engages the holding collar which in turn engages theplunger assembly.
 3. The method according to claim 2, further comprisingthe step of: providing said plunger assembly with a tapered end whichexpands the ring to fit over the shoulder when said holding collarengages the shoulder.